There is a continual push in the semiconductor industry for higher power IC devices, which require thermally enhanced packages. Heatspreader type designs cost effectively fulfill this need. Presently, 28 and 52 lead PLCC heatspreader packages exist and it is anticipated that further applications for SOIC, SOJ, QFP and other PLCC heatspreader packages will be available in the near future. Further, most standard IC leadframe designs would benefit from added protection of the critical wire bond surface during handling and shipment.
In the assembly of heatspreader packages, a heatspreader is generally affixed to the leads and flag area of each leadframe by an adhesive tape. A problem arises because the heatspreader, tape and leadframe are sandwiched together and pressed into place, generally under heat to activate the adhesive in the tape. The pressure and heat is applied directly to the upper surfaces of the leadframe, which includes wire bonding zones near the tip of each lead in each leadframe. The heat and pressure on the bonding zones creates scratching, dents, and other damage as well as leaving foreign matter and other contaminates thereon. This physical damage and contamination leads to visual quality problems, as well as latent functional problems, when the semiconductor die is wired to the leadframe due to inconsistent and in some cases poor wire bonding.